Toggle-locking tools are characterized by an arrangement of four pivots that permits the jaws of the tool to be locked about a work piece. The basic toggle-locking tool was invented by William Petersen and patented in 1924 as U.S. Pat. No. 1,489,458. That original tool, and improvements and variants of that tool made by Petersen and the company he founded, have been sold to the present day under the brand name “Vise Grip”. A central objective of all such tools is to combine the function of a vise with that of conventional pliers, enabling a worker to grip a work piece in the tool and then to lock and maintain the grip on the work piece upon releasing the gripping force. A shortcoming of conventional toggle-locking tools is that the holding force by which an object is held in the jaws of the tool is essentially limited by the compression force employed by the user in gripping a work piece, multiplied by such mechanical advantage as is provided by the design of the tool. In particular, this holding force may not readily be increased once the jaws of the tool have been locked about a work piece. Accordingly it is an objective of the present invention to provide a toggle-locking tool comprising means for enhancing the holding force of the tool far beyond the force initially employed to grip an object and to lock the jaws of the tool about that object.